At best, the competitor has behaved very poorly. Their removal of copyright claims in particular is a clear indication of malign intent.
But the author is correct in their assessment: the primary purpose of the GPL, and Free or Open Source licenses in general, is to provide a right to modify and distribute to anyone who obtains the software. There is no special protection for the original author(s).
Many projects have had a similar experience. Retaining a trademark on the project name gives the holder some parallel rights. Even projects as significant as Linux have had to deal with this.
At best, the competitor has behaved very poorly. Their removal of copyright claims in particular is a clear indication of malign intent.
But the author is correct in their assessment: the primary purpose of the GPL, and Free or Open Source licenses in general, is to provide a right to modify and distribute to anyone who obtains the software. There is no special protection for the original author(s).
Many projects have had a similar experience. Retaining a trademark on the project name gives the holder some parallel rights. Even projects as significant as Linux have had to deal with this.